Bill Gates's Open Letter to Hobbyists from the Homebrew Computer Club Newsletter, January 1976

An open letter is a letter that is intended to be read by a wide audience, or a letter intended for an individual, but that is nonetheless widely distributed intentionally.[1]

Open letters usually take the form of a letter addressed to an individual but provided to the public through newspapers and other media, such as a letter to the editor or blog.[2] Especially common are critical open letters addressed to political leaders.

Currently there are very few sites solely specialising in publishing open letters. However, there are community sites where visitors can publish their own letters and promote them to a wider audience.[3]

Letters patent are another form of open letter in which a legal document is both mailed to a person by the government, and publicized so that all are made aware of it. Open letters can also be addressed directly to a group rather than any individual.